In physics, a unit of pressure equal to 760 torr, 1013.25 millibars, or 1.01325 x 10⁵ newtons per square meter: The standard atmosphere is a unit of pressure, the pressure that holds up or supports a column of mercury 760 millimeters high at sea level and at 0°C.

The actual pressure exerted by he atmosphere fluctuates around this value, which is assumed to be standard at sea level and zero degrees centigrade/32 degrees Fahrenheit, and is used when dealing with very high pressures.

The terms used here are located in this unit.